Hi Ollie,
I've PMed you about coupon code btw, cheers.
The springs are green because thats the tape I used on them. Almost every set of "generic spring stilts" come with a black heat-shrunk layer around the spring. Once you've inspected your delivery and are happy with its condition then its recommended you "tape the springs". This is done quite simply by getting hold of electrical tape of your choice and wrapping it round and round the spring from top to bottom. I chose green, other mates have used Day-glo Pink, black, white, striped, red, blue, yellow - whatever you can get your hands on.
Mine however are a bright green fluff now!